L1 fault tolerant adaptive control of a hexacopter with control degradation

In this paper we present a nonlinear control framework for the attitude of a hexacopter system, which is able to cope with motor degradation. Approximate model inversion transforms the plant into an equivalent linear form. A linear error controller enables tracking of a designer chosen reference model. The control framework is augmented by an L1 adaptive controller, in order to cope with uncertainties. Due to the nature of the L1 controller, performance and robustness are decoupled, which allows for a fast and reliable compensation of faults. We present a condition on the control allocation in order to achieve attitude stabilization during hover. The performance of the control architecture is corroborated in numerical simulation using a high fidelity simulation model of a hexacopter system. After that flight test results with motor degradation are presented.